Venous thromboembolism (deep vein thrombosis and/or
pulmonary embolism) is a common disorder, which is estimated to
affect 900,000 patients each year in the United States. Approximately
one-third of these cases are fatal pulmonary emboli, and the remaining
two-thirds are nonfatal episodes of symptomatic deep vein thrombosis
or pulmonary embolism. The majority of fatal events occur as sudden
or abrupt death, underscoring the importance of prevention as the
critical strategy for reducing death from pulmonary embolism. Of
the estimated 600,000 cases of nonfatal venous thromboembolism each
year, approximately 60 percent present clinically as deep vein thrombosis
and 40 percent present as pulmonary embolism. Most clinically important
pulmonary emboli arise from proximal deep vein thrombosis (thrombosis
involving the popliteal, femoral, or iliac veins). Upper extremity
deep vein thrombosis also may lead to clinically important pulmonary
embolism. The clinical features of deep vein thrombosis and pulmonary
embolism are nonspecific. Objective diagnostic testing is required
to confirm or exclude the presence of venous thromboembolism. An
appropriately validated assay for plasma D-dimer, if available,
provides a simple, rapid, and cost-effective first-line exclusion
test in patients with low, unlikely, or intermediate clinical probability.
Compression ultrasonography of the proximal veins performed at presentation,
and if normal, repeated once 5 to 7 days later, can safely exclude
clinically important deep vein thrombosis in symptomatic patients.
In centers with the expertise, a single comprehensive evaluation of
the proximal and calf veins with duplex ultrasonography is sufficient.
If capability for combined computed tomographic angiography (CTA)
and computed tomographic venography (CTV) exists, it is the preferred
approach for most patients with suspected pulmonary embolism because
it provides a definitive basis to give or withhold antithrombotic
therapy in 90 percent of patients. CTA is not inferior to using
ventilation–perfusion lung scanning for excluding the diagnosis
of pulmonary embolism when either test is used together with venous ultrasonography
of the legs. Anticoagulant therapy is the preferred treatment for
most patients with acute venous thromboembolism. Initial treatment
with subcutaneous low-molecular-weight heparin or fondaparinux, followed
by long-term treatment with an oral vitamin K antagonist such as
warfarin sodium, is effective for preventing recurrent venous thromboembolism.
Use of low-molecular-weight heparin or fondaparinux enables outpatient
therapy and is the preferred initial therapy for most patients.
Treatment with low-molecular-weight heparin for at least 6 months
is preferred in cancer patients and should be continued if cancer
is not resolved. Thrombolytic therapy is indicated for patients
with pulmonary embolism who present with cardiovascular collapse
and in selected patients who have impaired right ventricular function.
Insertion of a vena cava filter is indicated for patients who have
an absolute contraindication to anticoagulant therapy or who have
recurrent venous thromboembolism despite adequate anticoagulant
treatment. Anticoagulant treatment should be continued for at least
3 months in patients with a first episode of venous thromboembolism
secondary to a reversible risk factor. Indefinite anticoagulant
therapy should be considered for patients with idiopathic venous thromboembolism,
certain thrombophilias, or recurrent venous thromboembolism.
Acronyms and Abbreviations